Liquid Aurora

As a lifelong skygazer I rarely see anything I don’t immediately recognize. This one gave me pause. I was out on the deck last night after a rain just checking the sky, and when I saw this display I had to grab my camera. My immediate impression was “That looks like an aurora!” But the view was to the west, over the the Hieroglyphic Mountains and, of course, aurorae are in the north. They also form at altitudes around 450 km (280 miles) — not below clouds. Nonetheless it was visually striking. The time was half an hour before sunset. Photo data: Canon 20D + 55 mm, f/11, 1/250 sec, ISO 400.

I watched the display for several minutes. It didn’t move much, and gradually got dimmer with more intense colors as the sunset progressed. The “aurora” was actually rainfall over Lake Pleasant illuminated from just the right angle by sunlight. The imminent sunset explains the pastel gold and red colors. Somewhere behind that mountain range there’s sunlight peeking through a gap in, or under, more distant clouds.

This isn’t the first time I’ve caught this effect. For example:

But in those cases the rain was so distant the streamers of precipitation blurred into one luminous mass. This rain was only 5 miles away so the striations were visible. It was also higher contrast than the others, due to the chance alignment of clouds providing shade and light exactly where needed.

So I figured Liquid Aurora was an apt title for this post. It’s not scientifically correct — real aurorae are composed of plasma, not liquid. This post is mostly about a pretty picture which, as you know, I enjoy sharing on occasion.

Next Week in Sky Lights ⇒ Carbon Capture

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Q&A: Carbon Capture